As is well known to those skilled in the art, particle sensors are devices, which measure the amount of and sizes of minute particles contained in air. The particle sensors are installed in various kinds of apparatuses, such as air conditioners, air cleaners, etc., which purify air or perform the operation of drawing air in and discharging it.
Such a particle sensor measures the amount and sizes of minute particles while an apparatus, such as an air cleaner having the particle sensor, is being operated, thus providing information about air pollution levels to the apparatus so that the apparatus can be effectively operated.
Referring to FIG. 1, a typical particle sensor 10 has an inlet 11 into which air is drawn, a detection chamber 12 provided to measure pollution levels of the air, and an outlet 13 through which the air that has its pollution levels measured is discharged to outside the particle sensor.
Generally, the particle sensor 10 measures the pollution levels of air using a method of applying light to air flowing by natural convection and not by forced convection. In this case, to ensure the accuracy of measurement, air drawn into the inlet 11 must flow towards the outlet 13 through the detection chamber 12 in the direction opposite that of gravity, that is, upwards. The reason for this is that air flowing by natural convection is moved upwards from the lower position to the upper position owing to differing densities of the air.
Here, a difference in density of air is caused by expansion of air due to heat generated from a resistor, which is a typical electronic component and is provided around the inlet 11. In other words, air drawn into the apparatus, such as the air cleaner, is expanded by heat and is thus reduced in density. The air that is reduced in density becomes lighter, thus moving upwards.
As such, the resistor, which is a typical electronic component and is provided around the inlet 11, serves as a heat source, so that air drawn into the inlet 11 is expanded by heat generated from the resistor and is thus moved upwards. At this time, pollution levels of the air are measured in the detection chamber 12 and, thereafter, the air is continuously moved upwards and discharged through the outlet 13 to the outside of the particle sensor.
Meanwhile, the air cleaner can be typically installed in a vertical direction or in a horizontal direction. Such orientation of the installation of the air cleaner may be changed in various manners depending on the individual tastes of users or the installation environment of the air cleaner. Here, the orientation of the particle sensor 10, which is installed in the air cleaner, is also changed depending on the orientation of the air cleaner. In other words, a straight line, which connects the inlet 11, the detection chamber 12 and the outlet 13 to each other, is oriented in the vertical or the horizontal direction depending on the orientation of the air cleaner.
However, in the case where the straight line that connects the inlet 11, the detection chamber 12 and the outlet 13 to each other is oriented in the horizontal direction, air which flows by natural convection cannot smoothly pass through the particle sensor. As a result, the pollution level of air cannot be precisely measured in the detection chamber 12.
That is, referring to FIG. 2, between a vertical (or a stand type) air cleaner 1 and a horizontal (or a table type) air cleaner 2, the orientations of the installed particle sensors 10 differ from each other, as described above.
Therefore, a particle sensor, which is constructed such that an inlet 11, a detection chamber 12 and an outlet 13 can be arranged in the vertical direction regardless of the orientation of an air cleaner, is required.